Group or Private
mmmk I can board (but never taken a lesson), however my g/f cannot. I would like to get her a lesson/lessons in NZ this year to get her to learn (i really dont want to teach her, as WW3 will result), and I would like to do the lesson as well (for fun and to support her). I can afford private lessons or group, but what do you think would be better for her progression? (she can already wakeboard well and surf).
mmmk I can board (but never taken a lesson), however my g/f cannot. I would like to get her a lesson/lessons in NZ this year to get her to learn (i really dont want to teach her, as WW3 will result), and I would like to do the lesson as well (for fun and to support her). I can afford private lessons or group, but what do you think would be better for her progression? (she can already wakeboard well and surf).
Private..in most cases
With her background she should pick up the basics fairly quickly…
Then , I hope you can keep up 
I am an instructor and I teach both group and private lessons. I find then equally helpful for the student/students. It depends on the way you learn. Like say you love attention and need constant feedback, then I would take a private. But if you prefer to blend in and watch other people and then learn for yourself, then a group lesson is for you.
For me I like to go with groups..You can really feed off other people and improve yourself
I love riding around with groups of people because it creates a bit of a competitive atmosphere with really challenges my skills
Privates are nice because you can get some one on one attention and they can focus on your progression
That’s my 2 cents worth
A first lesson I would suggest a group, it’s the cheaper route.
After the first lesson or two, private lessons are the way to go.
when buying group lessons, ask what the group size is. anything over 7 is huge for a snowboard lessons, and for that reason I would consider private.
When buying private lessons dont settle for any instructor, ask for the best, ask for a certified instructor.
and definitely when buying intermediate or upper level lessons demand a certified professional.